Frederic saunes waldron



March 4 1924.

F. B. WALDRON APPARATUS FOR GRINDING on POLISHING PLATE GLASS Original Filed Aug. 5,

inn-I fiient at right Reissuea Mar. 4, 1924.

FREDEBIC BARNES WALDRON, F PRESCOT, ENGLAND, ASSIGNOR TO PILKINGTON nno'rms LIMITED, or semi nm'rnm.

Original in. 1,870,246,

To all whom it ma concern:

Be it known t at I, FREDERIG BARNES WAumoN, a subject of the King of the United Kingdom of Great Britain and Ireland, and residing at Eccleston Park, Prescot, in the county of Lancaster, England, have invented new and useful Improvements in Ap aratus for Grinding or Polishing Plate glass, of which the following is a specification.

This invention relates to a paratus for rinding or polishing plate g ass and has or its object to rovide apparatus wherein labor, power an abrasive can be utilized 16 more efiiciently than has heretofore been possible with apparatus of other construc- 'tion.

In early forms of grinding and polishing apparatus, the glass was laid on a rectangu- 20 lar table, and reciprocating rubbers, fed with abrasive, were pressed on the glass and acted to grind, smooth and polish it, either the rubbers or the table being given a move- I angles to the reciprocating 26 movement so that the whole surface of the glass was uniforml acted on.

It was found t at higher powers and speeds could be em loyed in the o erations of grinding, smoot in and polis ing, by so adopting a rota in p ace of a reciprocating motion, an glass is now commonly ground, smoothed and polished by attachmg plates of rou h glass to the surface of a large circular ta le which is revolved un- 86 der two or more disk runners, while abrasive is supplied to the surface of the glass. The surface of the circular table is covered as far as possible by rectangular plates of glass of commercially useful sizes and then the 40 s aces left have to be filled up by pieces of g ass which are too small to be commercially useful, but serve the purpose of presenting a uniform surface on which the runners can rub. The 'nding is be un with coarse to sand and w en this stage 0 the grinding is com lets, the grinding is stopped and the san is washed oil and a finer grade of sand is sup lied, the process being afterward repreate with furt er different grades of sand. 0 he final stages of grinding, sometimes called smoothing, are then effected in a similar manner and on the same apparatus, by employing different grades of emery in 01 ST. HELENS, ENGLAND, A LIMITED LIABILITY COMIPANY APPARATUS FOR GRINDING OR. POLISHING PLATE GLASS.

dated. March 1, 1921, Serial No. 401,488, filed August 5, 1920. Application for reissue filed March 27, 1923. Serial No. 628,114.

place of sand. Where the table is driven by an electric motor, the speed of revolution of the table and the ower applied, are varied for each grade of abrasive so as to eifect the grinding and smoothin in the minimum time. When one side of t e glasshas been ground, the table is removed from the grindmg apparatus and brought to a polishing apparatus, and when the polishing has been completed, the table is again remove plates of glass turned over and re-laid on the table and the table is brought to the grinding apparatus and the process repeated.

The present invention among other features, combines the advantages of the rectan ular form of table employed in the ear forms of apparatus with the rotary motion employed in the later forms.

The whole process of grinding or polish: ing a side of glass is continuous and does not involve the aforementioned interruption of operation for change of abrasive, since the apparatus, without stoppa permits of the effective removal of eac grade of abrasive before the glass reaches that stage at which it is operated on by the next finer grade.

In the accompanying drawings, which are shown more or less diagrammatically- Figure 1 is a side elevation of one form of the apparatus, a portion thereof being omitted,

Fig. 2 is a section thereof on the line A.- A. looking from the left hand;

Fig. 3 is a longitudinal section on the line B. B. of Fig. 4 of a portion of the apparatus showing an alternative method of driving the tables, and

Fig. 4 is a transverse section of the same on the line C. C. of Fig. 3.

' Referring to Figs. 1 and 2, 1, 1 are the tables on which the plates of glass are laid, 2, 2 is a bed-plate serving-to support and guide the tables. The runners 3, 3, turn in bearings 4, 4, attached to cross girders 5, 5,

fixed on two longitudinal girders 6, 6, which are supported on cross girders 7, 7, resting on supports 8, 8. The runners are turne by any convenient mechanism such as the pulleys 9, 9, and are raised and lowered and their pressure on the glass regulated, by any of the methods commonly employed, such as d, the

11 is fixed to the underside of the said tables, and a pinion 12 gears with the rack 11 and is driven by any convenient mechanism such as a worm wheel 13 and worm 14, said driving means bein repeated as often as may be convenient a ong the length of the apparatus.

The tables 1, 1 are connected together by any convenient device such as pairs of overlapping lugs 15, through which cotters are driven. The tables under the runners 3 then form a continuous surface and, by means of the rack 11 and pinion 12, they are slowly passed underthe runners in the example illustrated from the left hand of the drawings towartf the right.

The runners are shown arranged in sets of two, the two'runners of each set having their axes one on each side of the centre line so that together they operate over the whole width of the tables. Either a single large runner, however, or such a group of runners as may be required to insure uniform grinding over the width of the table, may be employed, and will bedenoted hereinafter by the term set of runners.

Each set of runners is supplied with one grade of abrasive but where it is desired that the glass should be subjected to the action of one grade of abrasive for a longer time than that appertaining to the other grades of abrasive, two or more sets of runners may be supplied with this one grade of abrasive. In this way all the runners may be constantly operated at full power and speed without stoppage. It is generally desirable to let down the first set of runners on to the rough glass with gradually increasing pressure, but apart from this all the runners can operate continuously with a constant pressure.

r A space 16 is left between each set of runners, and the glass in its assage across this space, is washed clear of the abrasive employed with the immediately following set of runners where the preceding set employs a different grade of abrasive. By this means difl'erent grades of abrasive can be used simultan'eously throughout the machine and the process of grinding or polishing the glass, as distinguished from the customary process, is rendered continuous The space between the sets of runners using different grades of abrasive must be" suflicient to avoid abrasive thrown out by a runner under centrifugal force reaching the preceding or following runner.

The last set of runners shown at the right hand end of Fig. 1 is a set of polishing runners, and, though it is sometimes stated that the rou e commonly employed for polishing glass, oes not act as an abrasive and that the apparatus that passing from one end of the apparatus to the tinuous table,

the action of the runners is not a grinding action, yet in this specification the terms abrasive and grinding are taken to include the rouge or other medium used in polishing and the action of polishing respectively.

YVhen a table has passed under the whole series of sets of runners and has come to the right hand end of the apparatus, the glass is removed and the table then passed on to a trolley 17 and that table is then detached from the following tables and removed on the trolley, another trolley being placed to receive the next following table. The trolley is then brought to the left hand or start ing end of the apparatus, so as to bring the end of the table against the end of the first table on the apparatus as shown'at 18. The table is then attached to the first table on the apparatus, glass is laid thereon and the table then again passes under the whole series of runners 3.

The invention is not confined to the use of the trolleys shown, as any other convenient means of transportation may be em ployed, and instead of a rack and pinion the means employed to drive the tables may be 1 an endless chain engaging lugs on the tables. It is essential to the practical working of the series of tables in other, present a practically continuous unbroken) surface, without any difference of level between one end of a table and the adjacent end of the next table, so that the grinding and polishing runners may, at all points, operate on a practically continuous and level surface of glass. it 'is an essential feature of the invention that the tables be in sliding contact with the bed-plate 2, 2, the contacting surfaces both of the tables and bed-plate being accurately machined to a plane.

Figs. 3 and 4 show an alternative method of driving the tables 1, 1, in which the latter are not attached together to form a conbut follow each other so closely as to form a nearly continuous table.

For this reason The drawings show'only the supporting bed-plate 2, 2, without the overhead framework and runners, since these do not differ from those shown in Figs. 1 and 2.

Each table is provided with a air of lugs 19, 19, with which engage pro ections 20, 20, on an endless chain 21 running below the tables along the whole length of the apparatus.

The chain 21 is driven by one or both 'of a pair of chain wheels of which one is shown at 22, the drive being by any convenient means such as the gear wheel 23.

In this form of the apparatus, a table, after passing under the serles of runners, is automatically freed from the projections on the chain by reason of the chain descending to pass over the chain wheel, and, in order to engage a table with the chain at the starting end of the apparatus, it is suflicient to' ners is not required. Further, it permits ofeach grade of abrasive being easily recovered and re-graded, and, since only the glass has to be washed clear of the abrasive it permits of a more easy and thorough removal of the coarser abrasive than has heretofore been practicable. I

The rectangular sha avoids the necessity for spaces, as is necessar e of the tables ling the segmental with the usual circular table, with smal pieces of glass which are useless commercially and require power for grinding and labor in laying, and, further, as the glass is not subjected to centrifugal force it is more easy to attach it to the table. At the same time, the advantages of the rotary motion of the circular tables are secured b the rotary disk runners and enalifles'dhig powers and speeds to be emp o e '1 he device, therefore, combines the advantages of the rectangular'tables with those of the rotary tables. j

The disk runners may be of any desired kind and size and arranged in any suitable manner relatively to the tables and each other, and each may be driven by an indeendent motor, or a series of runners can be riven by belt or earing from a single motor or countershai t, the speeds being such as to rotate each set of runners at the speed best suited to the adbrasive used with it.

I am aware that it has heretofore been proposed to construct a so-called continuous glass grinding and polishing machine in which the tables for feeding the glass beneath the rinding and polishing runners are mounted on wheels adapted to travel on tracks, and in which the glass is cut to a size or sizes completely to cover each table. In

such a construction, due to the support of the tables on wheels, the great pressure exerted by the runners in their operation on the glass causes a relative motion of the adjacent ends of the tables which would inevitably fracture the glass lates if laid over the joints between the tab es. My machine is to be distinguished from such a construction in that the tables are slidingly su ported on fixed guides where there can no relative motion of the adjacent ends of tables and, consequently, in laying the glass on the tables, the joints can be ignored and the glass be laid over such joints, the tables forming in effect a continuous support for the lass. H iving described my invention, I declare that what I claim and desire to secure by Letters Patent is a 1. A paratus for grinding or polishing plate g ass consisting of a series of rectangular tables in contact each with its neighors forming a continuous support for the plates of glass and slidingly supported on fixed uides, a framework above the series of tab es, a series of sets of runners'on verticalshafts, bearings for the shafts attached to the framework, means for moving the series of tables continuously from one end to the other of the series of sets of runners, means for removing ,a table from the moving series of tables after it has left the last set of runners, and means for adding a table to the moving series of tables before the first set of runners, the sets of runners being so spaced apart as to permit of the effective washing away of the abrasive be tween any two sets using different grades.

2. Apparatus for grinding or polishing plateglass consisting of a series of rectangular tables in contact each with its neighbors forming a continuous support for the plates of glass and slidin ly supported on fixed guides, a 'framewor above the said series of tables, a series of sets of runners on vertical shafts, bearings for the shafts attached to the framework, a rack attached to the underside of each table and a gear wheel engaging the rack' to move the series of tables at uniform speed from one end to the other of the series of sets of runners.

In testimony whereof I have aflixed my signature hereto.

FREDERIO BARNES WALDRON. 

